I had at least one lucid dream a long time ago and the trigger for me was logic. What happened in the dream was not plausible and I became aware that it was a dream because of that and as a result I could control the dream until I woke up. Dreams for me are not as vivid as life, there is no direct rendering but rather I see an imperfect visual. I favor using my imagination when I am awake and let my brain take a rest from consciousness while I sleep and dream, allowing it to do its thing without my conscious interference.